Divergent Syntheses of 2-Aminonicotinonitriles and Pyrazolines by Copper-Catalyzed Cyclization of Oxime Ester
摘要:
Copper-catalyzed cyclization of an oxime ester toward divergent heterocycle synthesis is reported. Oxime ester serves as an enamine precursor to cyclize with malononitrile and aldehydes for access to 2-aminonicotinonitriles in a one-pot reaction, while cyclizing with N-sulfonylimines leads to synthesis of pyrazolines.
A complementary method for the preparation of 3,5-substituted pyrazoles in moderate to high yields has been explored via TfOH-induced addition of tosylhydrazones to the terminal alkynes. This acid-induced addition procedure might be an operationally safe alternative compared to typical 1,3-dipolar cycloaddition as there is no involvement of diazo compounds.
Divergent Syntheses of 2-Aminonicotinonitriles and Pyrazolines by Copper-Catalyzed Cyclization of Oxime Ester
作者:Qifan Wu、Yan Zhang、Sunliang Cui
DOI:10.1021/ol500094w
日期:2014.3.7
Copper-catalyzed cyclization of an oxime ester toward divergent heterocycle synthesis is reported. Oxime ester serves as an enamine precursor to cyclize with malononitrile and aldehydes for access to 2-aminonicotinonitriles in a one-pot reaction, while cyclizing with N-sulfonylimines leads to synthesis of pyrazolines.